As is well known, photographic systems have been provided for some time in which foreground and background scenes are photographed by separated cameras. The foreground scene is photographically or electronically combined with the background scene to form a composite picture or video signal. Such systems are illustrated in prior U.S. Pat. No. 3,902,798, and 3,914,540 which are incorporated by reference herein. In each of these systems, a foreground camera is maneuvered on an appropriate dolly to photograph the foreground, usually actors, to be used with a corresponding background scene. To accomplish this, it is necessary that the background camera be moved in accordance with movement of the foreground camera, taking into consideration the differences in size of the scenes and the geometry of the supporting structure for the two cameras. When using this type of composite photography, it is usually necessary for the cameras to move in a coordinated fashion to create the desired final photographic results. When such systems are used for television, coordination between the two cameras is not as critical as when the system is used for wide angle motion picture film which have a high visual detail level. In any event, there has been a substantial demand for the development of a system which would control the slave or background camera in accordance with the foreground camera without requiring that both cameras operate in unison or even at the same time. Thus, the use of a master unit on the foreground camera which drives a servo controlled slave unit on the background camera is not completely satisfactory although it works quite well and has enjoyed substantial commercial success.
The present invention relates to an improvement in controlling a remotely located electrical servo device by the use of stored data, as opposed to the more common master-slave concept. By using this system, the synchronization of the remote unit is improved and the remote unit may be operated at a different time or at any location away from the unit which generates information indicative of the position to be assumed by the remote servo device.